// This method contains all heap specific policy for invoking mark sweep.
// PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
// the heap. It will do nothing further. If we need to bail out for policy
// reasons, scavenge before full gc, or any other specialized behavior, it
// needs to be added here.
//
// Note that this method should only be called from the vm_thread while
// at a safepoint!
void PSMarkSweep::invoke(bool maximum_heap_compaction) {
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
assert(!Universe::heap()->is_gc_active(), "not reentrant");
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
GCCause::Cause gc_cause = heap->gc_cause();
PSAdaptiveSizePolicy* policy = heap->size_policy();
// Before each allocation/collection attempt, find out from the
// policy object if GCs are, on the whole, taking too long. If so,
// bail out without attempting a collection. The exceptions are
// for explicitly requested GC's.
if (!policy->gc_time_limit_exceeded() ||
GCCause::is_user_requested_gc(gc_cause) ||
GCCause::is_serviceability_requested_gc(gc_cause)) {
IsGCActiveMark mark;
if (ScavengeBeforeFullGC) {
PSScavenge::invoke_no_policy();
}
int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
PSMarkSweep::invoke_no_policy(maximum_heap_compaction);
}
}
// This method contains all heap specific policy for invoking scavenge.
// PSScavenge::invoke_no_policy() will do nothing but attempt to
// scavenge. It will not clean up after failed promotions, bail out if
// we've exceeded policy time limits, or any other special behavior.
// All such policy should be placed here.
//
// Note that this method should only be called from the vm_thread while
// at a safepoint!
void PSScavenge::invoke() {
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
assert(!Universe::heap()->is_gc_active(), "not reentrant");
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSAdaptiveSizePolicy* policy = heap->size_policy();
IsGCActiveMark mark;
bool scavenge_was_done = PSScavenge::invoke_no_policy();
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
if (UsePerfData)
counters->update_full_follows_scavenge(0);
if (!scavenge_was_done ||
policy->should_full_GC(heap->old_gen()->free_in_bytes())) {
if (UsePerfData)
counters->update_full_follows_scavenge(full_follows_scavenge);
GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
CollectorPolicy* cp = heap->collector_policy();
const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
if (UseParallelOldGC) {
PSParallelCompact::invoke_no_policy(clear_all_softrefs);
} else {
PSMarkSweep::invoke_no_policy(clear_all_softrefs);
}
}
}
bool PSScavenge::should_attempt_scavenge() {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
if (UsePerfData) {
counters->update_scavenge_skipped(not_skipped);
}
PSYoungGen* young_gen = heap->young_gen();
PSOldGen* old_gen = heap->old_gen();
if (!ScavengeWithObjectsInToSpace) {
// Do not attempt to promote unless to_space is empty
if (!young_gen->to_space()->is_empty()) {
_consecutive_skipped_scavenges++;
if (UsePerfData) {
counters->update_scavenge_skipped(to_space_not_empty);
}
return false;
}
}
// Test to see if the scavenge will likely fail.
PSAdaptiveSizePolicy* policy = heap->size_policy();
// A similar test is done in the policy's should_full_GC(). If this is
// changed, decide if that test should also be changed.
size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
bool result = promotion_estimate < old_gen->free_in_bytes();
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
" padded_average_promoted " SIZE_FORMAT
" free in old gen " SIZE_FORMAT,
(size_t) policy->average_promoted_in_bytes(),
(size_t) policy->padded_average_promoted_in_bytes(),
old_gen->free_in_bytes());
if (young_gen->used_in_bytes() <
(size_t) policy->padded_average_promoted_in_bytes()) {
gclog_or_tty->print_cr(" padded_promoted_average is greater"
" than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
}
}
if (result) {
_consecutive_skipped_scavenges = 0;
} else {
_consecutive_skipped_scavenges++;
if (UsePerfData) {
counters->update_scavenge_skipped(promoted_too_large);
}
}
return result;
}
size_t ASPSOldGen::available_for_contraction() {
size_t uncommitted_bytes = virtual_space()->uncommitted_size();
if (uncommitted_bytes != 0) {
return uncommitted_bytes;
}
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t gen_alignment = heap->old_gen_alignment();
PSAdaptiveSizePolicy* policy = heap->size_policy();
const size_t working_size =
used_in_bytes() + (size_t) policy->avg_promoted()->padded_average();
const size_t working_aligned = align_size_up(working_size, gen_alignment);
const size_t working_or_min = MAX2(working_aligned, min_gen_size());
if (working_or_min > reserved().byte_size()) {
// If the used or minimum gen size (aligned up) is greater
// than the total reserved size, then the space available
// for contraction should (after proper alignment) be 0
return 0;
}
const size_t max_contraction =
reserved().byte_size() - working_or_min;
// Use the "increment" fraction instead of the "decrement" fraction
// to allow the other gen to expand more aggressively. The
// "decrement" fraction is conservative because its intent is to
// only reduce the footprint.
size_t result = policy->promo_increment_aligned_down(max_contraction);
// Also adjust for inter-generational alignment
size_t result_aligned = align_size_down(result, gen_alignment);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("\nASPSOldGen::available_for_contraction:"
" %d K / 0x%x", result_aligned/K, result_aligned);
gclog_or_tty->print_cr(" reserved().byte_size() %d K / 0x%x ",
reserved().byte_size()/K, reserved().byte_size());
size_t working_promoted = (size_t) policy->avg_promoted()->padded_average();
gclog_or_tty->print_cr(" padded promoted %d K / 0x%x",
working_promoted/K, working_promoted);
gclog_or_tty->print_cr(" used %d K / 0x%x",
used_in_bytes()/K, used_in_bytes());
gclog_or_tty->print_cr(" min_gen_size() %d K / 0x%x",
min_gen_size()/K, min_gen_size());
gclog_or_tty->print_cr(" max_contraction %d K / 0x%x",
max_contraction/K, max_contraction);
gclog_or_tty->print_cr(" without alignment %d K / 0x%x",
policy->promo_increment(max_contraction)/K,
policy->promo_increment(max_contraction));
gclog_or_tty->print_cr(" alignment 0x%x", gen_alignment);
}
assert(result_aligned <= max_contraction, "arithmetic is wrong");
return result_aligned;
}
// Return the number of bytes the young gen is willing give up.
//
// Future implementations could check the survivors and if to_space is in the
// right place (below from_space), take a chunk from to_space.
size_t ASPSYoungGen::available_for_contraction() {
size_t uncommitted_bytes = virtual_space()->uncommitted_size();
if (uncommitted_bytes != 0) {
return uncommitted_bytes;
}
if (eden_space()->is_empty()) {
// Respect the minimum size for eden and for the young gen as a whole.
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t eden_alignment = heap->intra_heap_alignment();
const size_t gen_alignment = heap->young_gen_alignment();
assert(eden_space()->capacity_in_bytes() >= eden_alignment,
"Alignment is wrong");
size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
eden_avail = align_size_down(eden_avail, gen_alignment);
assert(virtual_space()->committed_size() >= min_gen_size(),
"minimum gen size is wrong");
size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
assert(virtual_space()->is_aligned(gen_avail), "not aligned");
const size_t max_contraction = MIN2(eden_avail, gen_avail);
// See comment for ASPSOldGen::available_for_contraction()
// for reasons the "increment" fraction is used.
PSAdaptiveSizePolicy* policy = heap->size_policy();
size_t result = policy->eden_increment_aligned_down(max_contraction);
size_t result_aligned = align_size_down(result, gen_alignment);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: %d K",
result_aligned/K);
gclog_or_tty->print_cr(" max_contraction %d K", max_contraction/K);
gclog_or_tty->print_cr(" eden_avail %d K", eden_avail/K);
gclog_or_tty->print_cr(" gen_avail %d K", gen_avail/K);
}
return result_aligned;
}
return 0;
}
// This method contains all heap specific policy for invoking scavenge.
// PSScavenge::invoke_no_policy() will do nothing but attempt to
// scavenge. It will not clean up after failed promotions, bail out if
// we've exceeded policy time limits, or any other special behavior.
// All such policy should be placed here.
//
// Note that this method should only be called from the vm_thread while
// at a safepoint!
void PSScavenge::invoke()
{
assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
assert(!Universe::heap()->is_gc_active(), "not reentrant");
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
PSAdaptiveSizePolicy* policy = heap->size_policy();
// Before each allocation/collection attempt, find out from the
// policy object if GCs are, on the whole, taking too long. If so,
// bail out without attempting a collection.
if (!policy->gc_time_limit_exceeded()) {
IsGCActiveMark mark;
bool scavenge_was_done = PSScavenge::invoke_no_policy();
PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
if (UsePerfData)
counters->update_full_follows_scavenge(0);
if (!scavenge_was_done ||
policy->should_full_GC(heap->old_gen()->free_in_bytes())) {
if (UsePerfData)
counters->update_full_follows_scavenge(full_follows_scavenge);
GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
if (UseParallelOldGC) {
PSParallelCompact::invoke_no_policy(false);
} else {
PSMarkSweep::invoke_no_policy(false);
}
}
}
}